Recently, a demand has arisen for silver halide photographic materials, and especially color photographic materials for cameras having excellent graininess and sharpness at high photographic speeds, and also having excellent storage properties, as typified by the ISO 400 photograhic materials (Super HG-400 manufactured by Fuji Photo Film Co., Ltd.) which have as high image quality as that of the ISO speed 100.
Methods in which photographically useful groups are bonded to the coupling position of a coupler via a timing group and released at an appropriate time and in the form of the image during photographic processing are known to improve image quality. These methods have been disclosed, for example, in U.S. Pat. No. 4,409,323 and JP-A-60-218645. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application".)
The methods disclosed involve the release of one molecule of a photographically useful group from one molecule of a coupler.
However, if these couplers are present in the film in large amounts, the film thickness of the photosensitive material is increased, and there is an adverse effect on sharpness and an increase in cost.
Couplers having two photographically useful groups which are present on different atoms of electron transfer timing groups are disclosed in U.S. Pat. No. 4,861,701, and couplers having two photographically useful groups which are present on a single carbon atom of a timing group are disclosed in JP-A-l-154057. However, these couplers release the photographically useful groups even by hydrolysis, and their stability is not sufficient.